IUVSTA 15th International Vacuum Congress (IVC-15), AVS 48th International Symposium (AVS-48), 11th International Conference on Solid Surfaces (ICSS-11)
    Semiconductors Monday Sessions
       Session SC+SS-MoM

Paper SC+SS-MoM2
Coexistence of Active and Passive Oxidation Areas on the Si(100) Surface under Oxygen Cluster Beam Impact

Monday, October 29, 2001, 10:00 am, Room 122

Session: Oxidation of Semiconductors
Presenter: D.V. Daineka, A.F. Ioffe Physicotechnical Institute, Russia
Authors: D.V. Daineka, A.F. Ioffe Physicotechnical Institute, Russia
F. Pradère, CNRS, Ecole Polytechnique, France
M. Chatelet, CNRS, Ecole Polytechnique, France
E. Fort, Universités Paris VI et Paris VII, France
Correspondent: Click to Email
The Si(100) oxidation by cluster beam impact has been studied in ultrahigh vacuum for surface temperatures from 850 to 1100°C. Neutral oxygen clusters with an average size of 2000 molecules and a translational energy of 0.26 eV/molecule were delivered by a supersonic beam with the maximal flux density of 10@super 15@ cluster/cm@super 2@s. The analysis of surface profiles after the beam exposure at T<1000°C shows that a circular groove is formed on the surface. The groove, resulting from surface etching via the reaction 2Si+O@sub 2@-> 2SiO(g), is characterized with a steep inner wall and a gradual decrease of its depth towards the outer edge. In the central part of the impact spot, surrounded by the groove, no surface etching occurs due to the formation of a protective oxide layer. The revealed effect is attributed to the gaussian flux density distribution in the cluster beam cross section. The abrupt drop of the etching rate at the inner wall of the groove corresponds to the transition from active to passive oxidation. Only active oxidation with formation of a single etch pit was observed at T>1000°C. The reaction is steady-state and close to first-order. It has been found that there is no pronounced temperature dependence of the etching rate, which is in contrast with the previous results obtained with molecular oxygen.@footnote 1,2@ Etching rates as high as 6 µm/min were measured for T>1000°C. This enhanced reaction efficiency is attributed to the role of the oxygen clusters. The obtained results show that the knowledge of the flux density distribution in the beam is extremely important when supersonic sources are used to study surface reactions. @FootnoteText@ @footnote 1@ Y. Ono, M. Tabe, H. Kageshima, Phys. Rev. B48(1993) 14291 @footnote 2@ S. Hildebrandt, A. Kraus, R. Kulla, H. Neddermeyer, Appl. Surf. Sci. 141(1999) 294 .